Continuously operating centrifugal machine



Jan. 29, 1957 H. J. VAN WEZEL 2,779,474

CONTINUOUSLY OPERATING CENTRIFUGAL MACHINE Filed June 8, 1954 2Sheets-Shes? l Jan. 29, 1957 H. J.'VAN WEZEL CONTINUOUSLY OPERATINGCENTRIFUGAL MACHINE 2 Sheets-Sheet 2 Filed June 8, l954 U i W ICONTINUOUSLY OPERATING CENTRIFUGAL MACHINE Herman J. van Wezel, Hengelo,Netherlands, assignor to Koninklijke Machinefabriek Gebr. Stork & Co. N.V., Hengelo, Netherlands Application June 8, 1954, Serial No. 435,319 gI Claims priority, application Netherlands June 19, 1953 3 Claims. (Cl.210-69) This invention relates to a continuously operating centrifugalmachine, having a screen drum, into which the mass to be treated iscontinuously supplied and in the screen drum of which a scraper devicerotates with an angular velocity slightly differing from that of thescreen drum. I

Centrifugal machines of this kind are known in which the solid substanceseparated in the screen drum is continuously conveyed along the screenwall towards the discharge end of the drum by the scraper device so thatthe scrapers also act as conveyor blades. In order to obtain saidconveying action the scrapers have to exert a heavy pressure in axialdirection on the solid particles for over coming the centrifugal actionso that danger of damaging the solid particles arises. Particularly withcrystalline masses, such as sugar, damage .of the crystals is a seriousdrawback.

The invention has for its object to improve a centrifugal machine of thekind referred to in such a manner that the layer of solid particlesdeposited on the drum wall may be scraped off continuously at full speedof the drum and be conveyed towards the discharge without be comingdamaged. According to the invention the mass to be treated is suppliedinto the screen drum along the whole height of the screen wall by one ormore feed members which rotate together with the scraper deviceconsisting of one or more scrapers operating along the whole height ofthe drum closely to the drum wall and loosening the deposited layer fromthe wall, the scraper or each scraper being provided with one or morenozzles discharging a compressed medium blowing the solid particlesscraped off from the screen wall towards the discharge end of the drum.As with said arrangement the scrapers do not exert a conveying actionthe power consumption will be small and the solid particles will not bedamaged.

The invention will be further described with reference to theaccompanying drawings illustrating an embodiment of the centrifugalmachine according to the invention.

Fig. l is a sectional elevation of the machine taken along the brokenline II of Fig. 2.

Fig. 2 is a horizontal section taken along the line H- II of Fig. l.

The centrifugal basket or drum 2 is secured on the shaft 1 with its hub3. The inner wall of the drum is constituted by a screen wall 4consisting of rings. Said rings leave small slots with respect to eachother for the passage of the liquid to be separated and are centered byvertical ribs 5 secured to the inner side of the drum. The outer wall ofthe drum 2 is conically widened in upward direction so that the liquidthrown on said wall is moved upwards by the centrifugal action and flowsover the rim 6 into the gutter 7 at the inner side of the stationaryouter drum 8.

The shaft 1 is surrounded by a hollow shaft 9 which at its upper end andits lower end is guided by bearings 10 on the shaft 1 and supported byan axial bearing 11. The

2,779,474 Patented Jan. 29, 1957 hollow shaft 9 carries a drum 12 havingan oval cross section and connected to the shaft by a bottom plate 13.Two diametrically opposed flat boxes 14 are secured to the oval drum 12at its largest diameter and extend throughout the height of the screenwall 4 but leave a discharge gap 15 with respect to the screen wall.Adjacent each box 14 a further box 16 is formed by a wall 17 alsosecured to the oval drum 12, said box 16 at its end facing the screenwall 4 being provided with a scraper 18 also extending throughout theheight of the screen wall. The scrapers 18 at their inner side areprovided with guide blades 19 directed downwards.

A cylinder 21) is secured in the interior of the oval drum 12 andcarries diametrically opposed sets of sprinklers 21, so that said latterare also rotating together with the hollow shaft 9. A gutter 22 forsupplying the mass to be treated discharges into the upper end of theoval drum 12 and a pipe 23 for supplying washing or treating liquidopens into the cylinder 20.

The shaft 1, which is driven by a motor or by any other suitable means,hangs in a bearing block 24 sup ported in a rubber buffer 25. A gear box26 is secured to the bearing block 24 so that said box isadapted tofollow the oscillations, if any, of the shafts 1 and 9. On the shaft 1 atoothed wheel 27 is secured which through the intermediary of two wheels29, 30 transmits its motion to a toothed wheel 28 secured on the hollowshaft 9. The gear ratio between the toothed wheels 27 and 28 is suchthat the difference between the speeds of the shaft 1 and 9, whichdetermines the duration of the treatment of the mass, is very small.Preferably the gear ratio of the toothed gearing is variable in order tovary the duration of the treatment at will.

For supplying compressed air or another compressed medium the lower partof shaft 1 is provided with a central bore 31 communicating by someradial hole 32, with a chamber 33 to which the boxes 16 are connected.

On the end of shaft .1 a stationary stuffing box 34 is mounted and saidstuffing box is provided with a connection 35 for a pipe or flexibletube supplying a compressed medium.

In the bottom plate 13 discharge openings 36 are provided near thescrapers 18 and in the lower end of the outer wall of drum 2 openings 37are provided. Said openings are located between guide plates 38.

The above described centrifugal machine operates as follows.

The mass to be treated is continuously delivered into the oval drum 12by means of the gutter 22 and is uniformly distributed over the heightof said drum under the centrifugal action. Due to the oval shape of thedrum wall the entering mass is always guided towards the deliveringboxes 14 in order to be deposited on the screen wall through gap 15. Thethickness of the deposited layer depends on the width of gap 15. As thescreen wall 4 moves relatively to the boxes 14 the mass is continuouslydeposited on the wall 4 and after a relative rotation of is removed fromthe wall 4 by the diametrically opposed scraper 18 and blown downwardsby compressed air or another compressed medium discharged along theblades 19 so that the mass enters the lower part of drum 2 through theopening 36. The removed mass entering the lower part of drum 2 is throwninto the stationary outer drum 8 through the openings 37 and collectedin the funnel 39. The separated liquid passes through the screen wall 4and flows over the rim 6 in order to be collected in the gutter 7.

During the separation from the liquid of the mass deposited on the wall4 said mass may be washed by water or treated by another liquiddischarged by sprinklers 21. By the centrifugal action the liquid isdischarged with such violence that an efiicient spraying of the liquidis secured.

Though in the illustrated. embodiment the compressed medium is suppliedby the hollow scraper box 16, a platelike scraper may be used and aseparate nozzle for the compressed medium may be mounted near thescraper.

Instead of vertically the centrifugal machine according to the inventionmay also be horizontally mounted.

What I claim is:

1. A continuously operating centrifugal machine, comthe side of thescraper facing the drum axis for dis charging amedium under pressure forblowing the solid particles detached from the screen wall by the scrapertoward the discharge end of the drum.

2. A continuously operating centrifugal machine, comprising a screendrum having a screen wall and a discharge end, feed members in said drumextending substantially along the whole height of the screen wall of thedrum, and a scraper device connected to said feed members and rotatablein the drum with an angular velocity slightly differing from that of thedrum, said scraping device being shaped as a hollow body having ascraping edge and extending substantially along the whole height of thescreen wall of the drum and being connected to a supply of a compressedmedium, one of the walls of saidbody facing the drum axis and consistingof blades inclined towards the discharge end of the drum said bladesbeing positioned so as to receive the compressed medium and direct thesolid particles detached fromthe screen wall by the scraper toward thedischarge end of the drum.

3. A continuously operating centrifugal machine, comprising a screendrum having a screen wall and a discharge end, a hollow feed box in saiddrum extending substantially along the whole height of the screen wallof the drum, a drum of oval section for receiving the mass to betreated, said feed box being secured to said oval drum at the largestdiameter thereof, and a scraper device connected to said feed box androtatable in the screen drum with an angular velocity slightly differingfrom that of the drum, said scraping device being shaped as a hollowbody having a scraping edge and extending substantially along the wholeheight of the screen wall of the drum and being connected to a supply ofa compressed medium, one of the walls of said body facing the drum axisand consisting of blades inclined towards the discharge end of the drumsaid blades being posi tioned so as to receive the compressed medium anddirect the solid particles detached from the screen wall by the scrapertoward the discharge end of the drum.

References Cited in the file of this patent UNITED STATES PATENTS568,821 Waring et al. Oct. 6, 1896 1,253,428 Salcines Jan. 15, 19181,572,420 Birchall Feb. 9, 1926 1,902,982 Abbott Mar. 28, 1933 2,056,886Pecker Oct. 6, 1936 2,312,829 Bird et al Mar. 2, 1943 FOREIGN PATENTS134,092 Germany Oct. 2, 1902 280,363 Great Britain Nov. 17, 1927 812,298France Feb. 1, 1937

